SharkTuner FAQ for the Porsche 928
The following FAQ has been compiled for your information, we hope you find it interesting and useful.
Q - Why use the SharkTuner, rather than using the RRFPR/FMU I am using at present with my modified 928 ?
A - The SharkTuner offers much more accurate mapping of fuelling at all points on the load/rpm maps, both at cruise and at WOT. This is something that linear law devices such as RRFPR or FMU cannot do. Use of the SharkTuner also ensures that the fuelling is optimised to the specific car under test. This can result in smoother running and more WOT power.
Q - I am using larger size injectors on my modified 928 and have a few problems - can the SharkTuner address these ?
A - Yes, using 30lb or 42lb injectors can cause problems at idle and low loads/rpm. If the fuel pressure is reduced sufficiently to achieve a reasonable idle, then their spray pattern suffers, and pick up response may be poor.. Special software techniques have been developed to solve these problems when remapping with the SharkTuner. It adjusts automatically for these larger adjustments when larger injectors are selected in the menu.
Q - Can't a "Piggy Back" device control the idle fuelling with larger injectors ?
A - The piggy back can reduce the idle pulse width to give a reasonable idle with high enough fuel pressure with 30# injectors, but with larger injectors the pulse width required is too short compared to the opening time of the injectors for it to be possible to obtain a reliable idle at all. This may cause problems with emissions testing.
Q - What are the advantages of the SharkTuner over a Piggy Back ?
A - Ease of use - the SharkTuner does not need any changes to the vehicle wiring at all, no cutting wires or tapping into signals. The SharkTuner is simply plugged into the diagnostic socket of the car, and also into the EPROM socket of the LH ECU. When the car is remapped, the new EPROM is installed, and the car is then returned to "stock".mechanically The SharkTuner has an Autotune function which will remap the LH ECU as you drive the car, to the A/F ratio required.
Q - I have heard that above a certain MAF voltage, it is not possible to adjust the fuelling. What is this limit, and how do you address this problem ?
A - This is correct. The MAF can measure airflows well above 700bhp, the problem is in the LH hardware. Above 6v from the MAF a standard LH ECU cannot register increases in MAF voltage..This corresponds to about 450bhp at the crankshaft. We have solved this problem with a modified MAF - the "SuperMAF". This retains the same voltage at idle, but compresses the upper range progressively to allow accurate mapping up to 7.5v (in excess of 600bhp crank).
We can upgrade you standard MAF to SuperMAF specification for $100USD asuming your MAF is in good condition.
Q - Can I use a RRFPR/FMU to get the fuelling I require at high loads, and just use the SharkTuner to optimise idle and cruise mapping without using a SuperMAF ?
A - With 42lb injectors, you will be able to make approximately 500bhp crank using the standard 928 fuel pressure system with a SuperMAF. Using a standard MAF you may need to raise fuel pressure above about 450bhp crank where the LH ECU cannot track MAF voltage increases. The required increase in pressure could be achieved with an RRFPR. The rise needed will be much less than would have been necessary without the remapping using the SharkTuner.
Q - Why can't I just attenuate the voltage from a standard MAF to be able to map the high load end of its range ?
A - Because if the idle voltage drops too low, the LH ECU goes into "limp home" mode, as it decides the MAF is faulty.
Q - Why do I have to install a Wideband O2 sensor and electronics to use the SharkTuner ?
A - A narrow band O2 sensor does not have the measurement accuracy or range to allow correct remapping to be achieved. A WBO2 input is required to use the Autotune feature. In theory you could manipulate the fuel maps with the SharkTuner manually, but with only a narrow band indication, this would be very difficult, and could result in a lean condition and the risk of engine damage.
Q - I have catalytic converters on my 928, which I have to retain for emissions reasons. If I install a wideband O2 system for remapping, can I remap while working closed loop, and how does the SharkTuner allow this ?
A - Both the Innovate LC-1/LM-1 and the TechEdge WBo2 systems have a simulated narrow band output voltage that replicates the narrow band curve, and this can be plugged into the standard O2 sensor plug on your 928. Full details are in the SharkTuner User Manual.
Q - Can the SharkTuner also remap ignition ?
A - Yes the SharkTuner EZK option is now available. The same SharkTuner hardware is used with upgraded sofwtare to remap the EZK ECU.
Q - Does the SharkTuner come with all the leads required ?
A - It comes with the special diagnostic connector lead that powers the SharkTuner, and also provides the main data interface between it and the laptop. We also provide a DB9 serial cable to connect from the serial port of the laptop to the SharkTuner If you are using an LC-1 or LM-1 WBO2 system, and specify this when ordering, then a flying stereo jack lead is supplied to interface to the LM-1/LC-1.You may need to source an interface cable to connect from the simulated narrow band output from the LC-1/LM-1 to the 3 way O2 sensor connector of your 928 if you are intending to run closed loop. We can advise you on this, and supply such leads to special order.
Q - Does the SharkTuner come with a User Manual ?
A - Yes, a comprehensive 62 page User Manual is provided on a CD-ROM, which also contains all the required installation software.
Q - Can you provide special features such as alternative idle speeds, interface for other WBO2 systems etc ?
A - Yes, we would provide such features if they are feasible. We want to develop the product based on user requirements, and would value your feedback on the product.